Molding press



Nov. 20, 1945;

F.'J. STOKES, JR, ETAL.

MOLDING PRESS led June 15, 1942 5 Sheets-Sheet 1 Zjwum hobs FRANCIS JSTOKES, Jr.

F. J. STOKES, JR., ET AL MOLDING PRESS Filed June 15, 1942 3Sheets-Sheet 3 FRRN C15 J. STOKESJY. LAWRENCE HJBPQLEY Patentecl Nov.20, 1945 MOLDING mess Francis J. Stokes, Jr., Philadelphia, and LawrenceH. Bailey, Cheltenham, Pa., assignors to F. J. Stokes Machine Company, acorporation of Pennsylvania 1 Application June 15, 1942, Serial No.447,110

12 Claims.

This invention relates to molding presses for compressing granular orpowdered material in the cold state, into form-retaining shapes. Theinvention is useful in forming pellets, tablets and preforms, and alsofor forming h'ollow molded articles, such as hearing bushings, ofcomminuted materials are compressed by the upper punch" only, the bottomof the compressed piece is conslderably-softer'than the top. Thiscondition has been recognized from the time when the first presseswere'developed to do work of this sort.

A variety of methods have been worked out to remedy this condition. Onecommon method is to have the lower punch move upward in the die at thesame time that the upper punch compresses the material, so as to applypressure uniformly to both top and bottom of the piece, see StokesReissue Patent No. 17,842. Although this method is satisfactory, itrequires-a press with duplicate pressing mechanism, one for the upperand one for the lower punches, and there are complications in designinga press wherein the lower punch moves under, compression and then laterejects the finished part, these movements all being capable of easyadjustment to handle different size and different thickness pieces.Al--' though rotary type presses such as described in Stokes Patent No.610,029,, compress material from both top and bottom, these presses-arenot adaptable to the heavy pressures required for compressing materialssuch as powdered metals, ceramics, carbon, etc.

Another common method to achieve uniform density in the pieces is toresort to a floating die. A floating dieJs one which moves down around astationary lower punch, during compression, and thus simulates theaction of the lower punch moving upward during compression. There arevarious methods of operating floating dies. The simplest method is totemporarilysupport the die on. blocks and then after the upper punch hascompressed the material sufliciently to build up a certain amount offriction between the material and the die wall, the supporting blocksare withdrawn and the die floats downward as the upper punchcompresses,the position of the die being determined by the frictional forces set upbetween the material and the die wall. This is termed a full floatingdie. The disadvantage of this method is that material must be compressedto a considerable extent before the die will be supported by thefriction of the material, and furthermore the method is rather difflcultto work out on a fully automatic basis, such as is required for highproduction. In many cases, the die is supported on springs which supportthe weight of the die, and which permit the die to float downward as thefriction of the material builds up. The objection in this case-is thatthe springs do not function uniformly, and the guides that keep the diein proper position in relation to the punches, often become clogged withdust and dirt which prevents them from moving freely, and as a resultthe die may be prevented from floating at all. A hydraulic cylinder issometimes substituted for springs, these hydraulic cylinders beingconnected to an accumulator system so as to simulate the action ofsprings. Hydraulic cylinders are also used in some cases to actuallymove the die down under forced pressure, but this.

involves rather complicated hydraulic equipment, and the action is notuniform.

An object of thepresent invention is to devise a molding press employinga floating die with two cooperating plungers or punches, and embodyingmeans for positively controlling the relative movement between the dieand the two punches. By controlling the relative movements between thedie and the two punches, the formed article has the same densitycharacteristic on each side of its central transverse plane.

According to this invention, the rates of movement of the two puncheswith respect to the die may be made equal or unequal to control thedensity characteristic of the article with respect to the upper andlower ends of the article. In other words, where the two punches enterthe die cavity with the same speed, the plane of lowest density will belocated substantially at th'e middle horizontal plane of the article,and by making one punch travel faster than the other, the plane oflowest density in the article may be made to shift toone side or theother of the central plane.

This feature is useful for obtaining the same density ,in both ends ofan article where one end is of a diiferent diameter from theother endand the sections of different diameters are of different lengths.

In the preferred form of the invention a lever system is mounted on thepress, so that the downward motion of the upper punch automaticallyforces the die downward at the same time and in the proper relation tothe motion of the punch. The lever system is designed so that the diestarts to move down as soon as the upper punch enters this method isthat thevdie moves in exact relation with the upper and lower punch, andconsequently duplicates exactly the movements that would be obtained ifthe die were kept stationary and the upper and lower punches movedtogether at the same rate during compression. Furthermore, the die ismoved positively regardless of any friction in the die guides or betweenthe lower punch and the die.

Another feature of the present invention is that on the opening movementof the press, relative movement between the die and the lower punch isdiscontinued before the die leaves the lower punch, thus keeping thelower end of the die cavity closed for receiving a new charge, but

the upper punch continues its movement to the point of maximumseparation of the two punch elements. Such an arrangement provides amaximum clearance between the upper punch and the die for a givenseparation of the two punches, thus providing adequate clearance forejecting the molded article and for operation of the loading device.

Another feature of the invention is the provision of a core-rod which ismounted in fixed relation to the floating die and moves with the die. Itis important that the core-rod be mounted for movement with the floatingdie, inasmuch as the molding material builds up frictional resistancewith the core-rod wall Just as it does with the die wall. Heretofore, inpressesemploying floating dies, core-rods have been supported from somefixed part of the press, or else they have been mounted on springs whichpermit the rod to move downward as the material builds up resistancearound it. Such arrangements are not altogether satisfactory for thereason stated heretofore in discussing stationary dies andspring-mounted dies.

Another object is to provide a compressible section in the operatingconnection to the movable punch of the press to secure uniform densityof the molded articles and to prevent breaking of the press in the eventof excessive pressures being developed during molding. For this purpose,a compressible link is provided and is normally maintained in extendedposition by fluid under pressure supplied from a pneumatic accumulatorcylinder. ments, the fluid under pressure has been supplied through aflexible tubing connected to a moving part of the press. Sucharrangements are hazardous as the tube is likely to break at one time oranother, and particularly inasmuch as it must flex with each stroke ofthe press. This difllculty is overcome in the present invention byproviding an accumulator cylinder of relatively small size operatingathigh pressure and mounting the cylinder directly on the compressiblelink so that it moves therewith.

A preferred construction of our invention and certain modificationsthereof are illustrated in the accompanying drawings in which Figure lis a side elevation of a press embodying the preferred construction, thedetails of con.

struction of a compressible link forming part of the operating togglefor the press being shown in section;

Figure 2 is a front elevation of the press shown in Figure 1, with thefeeding device removed;

Figure 3 is a fragmentary view showing the details of construction ofthe cooperating mold parts, part of the view being a sectional viewtaken along a central transverse plane as viewed from the left side ofFigure 1; and

Figures 4 and 5 are fragmentary views showing, in side elevation,modified arrangements for positively moving the floating die member at adefinite speed related to the movement of the reciprocating punch.

Referring to the drawings. the press has a main supporting frameindicated generally by reference numeral l. Preferably the frame isformed of a single casting having two vertical side members I a and lbjoined at the top by a portion lo and at the bottom by a portion Id. Apower shaft 2 is journaled transversely of the two frame members la andlb near the top of the frame as shown. This power shaft is driven fromany suitable source of power through suitable speed reducing gears orpulleys, not shown. A platen 3 of the press, preferably the upperplaten, is mounted for vertical reciprocation by a suitable connectionto the power shaft 2. In the construction shown, the platen 3 isprovided with parallel vertically extending bosses or arms 3w'and 3b onopposite sides thereof and positioned in suitable guiding grooves formedin part by guide plates 3a and 3b secured to frame In previousarrangeconnected links.

members la and lb respectively. Various connections may be employed fortranslating the rotary movement of the power shaft 2 into reciprocatingmovement of platen 3, but the preferred construction shown in thedrawings involves a toggle and crank arrangement. The platen 3 issupported from the frame I by a. toggle construction consisting of twopivotally The first link 4 of the toggle is pivotally supported at itsupper end on a pintle .la supported by the frame I, and the lower end oflink 4 is pivotally connected by means of a pintle 4b to the second linkof the toggle which in turn is pivotally connected to the platen 3. Thesecond link of the toggle is formed of a special construction whichpermits a shortening of the link when the pressure developed on theplaten exceeds a predetermined limit. It is obvious, of course, that arigid link may be employed if desired.

The second link of the toggle is shown in section in Figure 1. Itconsists of two sections connected together in telescopic relation andincludg a hydraulic piston for forcing the two sections apart under apredetermined pressure. In the construction shown, the second linkinvolves a cylinder 5 pivotally connected at its lower end to the platen3 by means of a pintle 5a.. Mounted within the cylinder 5 is a piston5b,

- end of the piston rod 511 is provided with a connecting head ie whichis pivotally joined to the linklbyapintle 4b. Thepistonrodldisprovidedwith a flange Id by which the rod may be rotated to adjust the length ofthe second toggle link, it being understood that the piston rod id isrotatable with respect to the head 5e while remaining connected thereto.

A pressure chamber if is mounted on the her is partly filled with oil orother fluids shown, and the space above the oil is filled with asuitable gas under pressure. The procedure for filling chamber if iseriplained hereinafter.

The pintle lb is connected by a link 8 to a crank (or cam) in. driven byor embodied in the power shaft 2. Rotation of the shaft 2 causes the endof link 6 to travel around the circle 2a" which represents the path oftravel of the crank pin to, and this movement of the link 6 causes thetoggle I-5 to operate between the extended and collapsed positions, thuscausing platen 3 to reciprocate vertically.

A floating die table I is mounted for vertical movement below the platen3 and is guided by a pair of parallel guide rods 8a and 8b passingthrough sleeves Ia and lb on die table I and being secured insuitablebosses la, la" and lb,

lb" provided on vertical frame members In and lb respectively. Die tableI is normally urged upwardly by a pair of coil springs 92 and El)surrounding guide rods 8a and 8b and resting on lower bosses Ia" andlb". The upward movement of the die table is limited by one or more setscrews Ic having threaded engagement with the die table I and arrangedto bear against fixed in position within the. cavity by means of aabutments Ie carried by the vertical frame membars. The normal positionof the die table I may be adjusted by adjusting the stop screws Ic. Thedie table I carries the die part III of the mold which in the exampleillustrated consists of a simple cylindrical element III.

The upper punch Illa is carried by platen 3. For molding annular ringsof material, this punch assumes the form of an annular member as shown.

The lower member or shaft II mounted in a vertical position in the baseof the frame in line with the die In. Shaft II is guided for verticalreciprocating movement by a bearing Ila formed in the base Id of theframe, and also by a suitable hearing formed in the die table I. vAportion of the shaft is threaded as shown at I lb, and an adjustable nutHe is mounted on the threaded portion main stationary for the majorportion of the molding cycle, but moves the shaft upwardly, after thearticle has been formed, for the purpose of ejecting the article, andthen returns the shaft to its normal position before a new charge ofmaterial is supplied to the die cavity. Nut He should be adjusted sothat the upper end of punch Ilb is flush with the surface of table Iwhen cam It operates the punch to its upper position.

In the formation of solid articles, the lower punch Illb carried by theupper end of shaft II would be a solid punch having the shape of thelower face of the article. In the formation of hollow articles, it isnecessary to provide a core member which remains stationary with respectto the die II carried by the die table I. Where it is desired to moldhollow articles such as annular rings, as in the machine illustrated, itis necessary to provide a core-rod t3 supported centrally of the die IIIand in fixed relation to the die and die table I. For-supporting thecore-rod I3, a crossbar Illa is positioned in a longitudinal slot.

'Hd formed in shaft III and is adjustably sup-' ported from die table Iby a pair of tie rods lilb and lie. The core-rod i3 is removably securedto the crossbar I31; and its upper end lies in the common plane of theupper surface of die table I and the upper end of die It. With theconstruction described immediately above, it is clear that shaft l I maybe reciprocated vertically to eject the article while the core-rod i3 isheld in fixed relation with respect to the die lll.

The lower end ofahaft it extends into a cavity lid formed in the baseof'the frame and normally rests upon a plate ll positioned in the cavitylld', see Figure 3. The plate It is helg pa of set screws Ma and libhaving threaded engagement with the plate and abutting against the upperwall of the cavity. For the purpose of adjusting the height of the plateIt, one or more shim plates He may be inserted beneath the plate I4.This construction provides for adjustment of the normal position of thelower punch Illb within the die III, thereby fixing the volume 4 of thecharge-receiving cavity, the position of the lower punch being varied byvarying the thickpunch Illb is carried by a tubular '-ginsto ness ornumber of shim plates Me. It will be understood that die table I mayalso be adjusted with respect to shaft II to vary the volume of thecharge-receiving cavity.

As the punch Illa moves downwardly and becompress the material in dielllyit is desired to positively move the die table I downwardlysimultaneously and at a speed having a predetermined relation to thespeed of movement of the punch Illa. The preferred arrangement of theshaft. Shaft II is moved upwardly by means of a rocking lever l2pivotally mounted on an axis lie in the base of the frame I. The leverI2 is bifurcated at the forward end, and the two arms I2a and I2!)are'positioned on opposite sides of shaft I I and engage theundersurface of nut lie. The shaft I l remains stationary durforsecuring this result will now he described. A pair of brackets I50. andlib are adjustably supported on rods 8c and 8b by sleeve elementsforming part of thebrackets, and a. shaft I5 is journaled in bearingscarried by these brackets, the shaft being arranged somewhat forward ofthe press as shown in Figure 1. A lever I50 is keyed to the shaft l5 andextends back towards the press and into the-.space between the platen 3and the die table I. A roller ltd is mounted at the end of lever I50 inthe path of an adjustable abutmentscrew 3c carried by upper platen 3. Apair of parallel arms or levers use and lGb are keyed or otherwise fixedto the ends of shaft I5, and the free ends of these levers are providedwith rollers IGa' and lBb' which enga e the upper surface of die table Ias shown in Figure 1.

to open the mold, and additional -by'ejecting the molded article fromLevers lic, lid and lib are maintained in fixed relation with respect toeach other, but are rotated about the axis of shaft I! by movement ofthe platen 3 after engagement of screw 30 with roller lid. on thedownward stroke of platen 3, the platen first takes up the gap betweenstop screw 30 and roller lid on lever I 50. Contact between these twoelements is arranged to occur substantially simultaneously with theentrance of the punch 10a in the die 10. Further movement of platen 3'forces levers I50, Ilia and l6b to rotate in a clockwise direction aboutthe axis of shaft l5, and rotation of levers Ilia and I 6b forces dietable 1 and die I!) downwardly at a predetermined speed related to thespeed of platen 3. Where it is desired toform the molded article with asymmetrical density characteristic from each end, the table I should belowered at substantially one-half the speed of movement of platen 3, andthis relation will be obtained where arms Ilia and I6b have an effectivelength equal to substantially one-half the effective length of lever ic.With such an arrangement, the transverse plane of lowest density in themolded article will fall substantially at the middle of the article. Ifit is desired to shift this plane towards one end or the Other of thearticle, this may be done by varying the length of -arms Na and the libwith respect to the length of the arm I50.

Sleeves la and lb are maintained in any desired position by suitable setscrews threaded in the sleeves andengagingthe guide rods 8a and 81).These set screws need not be relied upon entirely to withstand theupward thrust of springs 9a and 9b when the platen 3 is moved upwardlystops are Drovided on rods 8a and 8b in the form of collars 8c and 8dadjustably clamped to rods 8a and 81) respectively. These collars areprovided with stop screws 80' and 8d end of the sleevessupportingbrackets H11 and i5b. It will be seen that the upward thrust of springs9a and 9b, and the upward thrust of shaft ll during election of themolded article, is taken up by adjustable stops 1e, 8e and 8d.

For the purpose of supplying molding material to the die I 0, a hopperI1 is suitably supported from the die table 1 and is movable therewith.The lower end of the hopper is provided with an oscillating shoe I'Iawhich has its discharge end in contact with the upper surface of dietable 1 and isnormally closed by the die table. A suitablecam and leverarrangement operated by shaft 2 causes the feeding shoe to shift into ahaving threaded engagement therewith and positioned to engage the upperposithm over the die cavity when the upper punch [0a has been raised acertain distance above die I; and, after shaking the shoe to fill thecavity with molding material, the cam returns the shoe to one side ofthe cavity where it remains until another feeding operation.

After the die cavity has received its charge of material, the platen 3moves downwardly and compresses the material in die II by the punchIlla, the die I0 being simultaneously lowered with the downward movementof the punch. During the return movement of platen 3, and after the"punch Illa has been withdrawn from the die cavity, the cam 21) lever l2and cause il until the upper end of lower punch lllb comes flush withthe upper surface of the die Hi, therethe die ID. The next operation ofthe feeding shoe pushes is eifective to operate rocking the upwardmovement of shaft is pumped into chamber the molded article to one sideand into the chute 'ld formed at one side of the die table I. This chuteconducts the molded article to a suitable receptacle. not shown.

In operation of the press, molding material may become lodged in theclearance space between the die l0 and the lower punch llb and preventthe punch from returning to its normal position by the action of gravityafter each election operation. For the purpose of securing proper returnof the lowe punch to its normal position after each ejection, the punchis normally biased downwardiy by means of a pair of springs Ila and Ilb,acting on a pair of levers "a and lab ivotally supported on, bosses la"and lb" respectively. The inner ends of lever Na and l9b pressdownwardly against a pair of pins 20a and 20b set in shaft I I. 'Anyother suitable arrangement may be employed to return shaft II to itsnormal position; for example, instead of using springs, a suitable camoperated by shaft 2 may be used to positively return the shaft to itsposition.

The pressure developed between cylinder 5 and piston 5b from thepressure chamber 5! should be sufficiently large to prevent shorteningof the lower toggle link where the molding pressure does not exceed thenormal pressure required for the molding operation. If, however, platen3 meets a resistance in excess of the normal molding pressure, thepressure developed within chamber 5! should permit piston 5b to advancein cylinder 5 and thus avoid breakage of the mold parts or parts of thepress. The amount of pressure to be developed in chamber II will, ofcourse, depend on a number of factors such as the molding pressure andthe effective area of piston 5b. Since the piston 5b is embodied in thelink construction of the toggle, it is desirable to reduce the size ofthe piston as much as possible, and it is also desirable to use apressure chamber U of small volume. Accordingly, these considerationscall for a relatively high pressure within. chamber If, and such highpressures may be obtained by the following procedure. Before introducingthe liquid in accumulator chamber 5f, the chamber is first filled withnitrogen gas from a commercial container in which the gas is stored at apressure of about 2000 pounds After this, and while the gas 5! ismaintained at approximately 2000 pounds per square inch, oil or othersuitable sealing liquid 5) under pressure. The pumping of the oil intochamber 5f causes a further compression of the gas within the container,and by such procedure it is possible to double the pressure or toincrease it to any desired amount within the limits of the press.

In Figure 4 is shown a modification of the arrangement for securingpositive movement of the die table during the compression stroke. Inthis figure, elements which correspond to like elements in Figures 1 and2 are indicated by like reference numerals. The die table 1 is normallyurged upwardly against adjustable stops 1c-le and -811 by springs and9b, as in Figures 1 and 2. The arrangement for moving the die tabledownwardly against the action of springs 9a and 9b involves a lever 2ipivoted at an intermediate point 2la to die table I. A roller 2lb isprovided at the inner end of lever 2i and arranged in the path of travelof adjustable screw- 3c carried y blaten 3 or an extension thereof. Theouter end of lever 2| is restrained against rotation about the axis 2Iaby a link 22 pivotally connecting the left end of lever 2| to a suitablet by screw 30 substantially simultaneously with the entrance of theupper punch into the die. If

the pivotal axis 2|a is arranged midway between the point of connectionof link 22 to the lever 2| and the pivotal axis of roller 2lb, thenlever 2i will cause die table I to move downwardly at 'onehalf the speedof the downward movement of. platen 3. By shitting the point of pivotalconnection between the die table and the lever 2| so as to vary thelever arms on opposite sides of the pivotal point, the relation betweenthe speed oi movement of the die table I with respect to the platen 3may be varied.

Another possible arrangement for securing posi-- tive downward movementof the die table I at one-half the speed of platen 3 is illustrated inFigure 5. In this arrangement, the die table is urged upwardly againstadjustable stops in the same manner as in Figure 4. Instead of using alever for lowering the die table by movement of the platen 3, a spurgear 23 is rotatably mounted on die table 1 and is positioned betweenand engages two racks 24 and 25. Rack 24 is secured to a fixed part ofthe frame and passes through a guide 24:: secured to the table 1. Back25 is arranged parallel with rack 24 and is guided by a pair of guides25a and 25b carried by table 1, the rack 25 being positioned directly inthe line of travel of screw 3c carried by platen 3 or an extensionthereof. In actual practice, the arrangement involving the elements 23,24, 25, etc., would be duplicated on the opposite side of the table I.

In the operation of Figure 5, during downward movement of the platen 3,screw 30 will engage the upper end of rack 25 substantially at the sametime that punch I Ila enters die It, and thereafter the die table I willbe driven downwardly at one-half the speed of movement of the platen 3.By using a double-gear instead of the single gear 23 and having rack 24engage one part of the double gear of one diameter and raclr 25 engagethe other part of the gear of a different diameter, it is possible tofix the rate oi movement of the table I to have any desired relation tothe speed of platen 3. V

Certain advantages are obtained in returning the die table I to itsupper position by means of springs 9a and 9b and limiting the upwardmovement by means of adjustable stops, one advantage being that agreater clearance space is obtained between the upper punch Illa and theupper surface-of die table I when the platen is in its upper position,thereby facilitating the loading or feeding operation.

Also, the die table is held stationary and in fixed relation .withrespect The pressdescribed herein is adaptable for the molding of avariety of articles of different shapes and sizes. It is obvious thatthe mold parts In,

Ila and "lb may be modified to produce articles 01 different shapes,either solid or hollow. The

volume of the charge-receiving cavity may be adl4, or by adjustment ofthe length of the lower link in the toggle 4-5.

In the constructions described herein, the die table I as well as thedie I0 is positively moved towards the stationary punch, but it isobvious that the table 1 may remain tationary and it is only necessaryfor the die H! to be movable towards the stationary punch. An obviousmodification of the invention would involve an arrange-.

ment where the table I is adjustably secured to guide rods 8a and 8b,and the die It! is slidably mounted in a bore formed in table I in linewith upper punch Illa, the die being urged upwardly against an abutmentby a suitable spring to normally hold the die in its upper position withits upper end fiush with the upper surface of table I. The die would bemoved downwardly against the action of the biasing spring by a suitableconnection between the die and lever arms i611 and 16b.

The springs 9a and 911 may be omitted, and the die table 1 may bereturned to its normal position by a suitable connection to the upperpunch.

While the invention has been shown in connection with atoggle type ofpress, it will be understood that the invention may be applied to anytype of reciprocating press. Also, while the illustrated embodiments ofthe invention employ only a single-acting upper punch and single-actinglower punch, the invention is useful in presses having multiple-actingupper or lower punches wherein one punch is movable within another.

What we claim is:

1. A molding press comprising, in combination, a reciprocative diehaving a mold cavity in the form of a bore therethrough, a normallystationary punch positioned in one end of said cavity, means fornormally holding said reciprocam tive die in a predeterminedcavity-forming position with respect to said stationary punch, areciprocative punch positioned to enter the other punch.

2. A molding press comprising, in. combination, a reciprocative diehaving a mold cavity in the form of a bore therethrough, a normallystationary punch positioned in one end of said cav- .ity, biasing meansacting in a direction to separate said die and stationary punch, meansfor limiting the separation of said die and stationary i punch and fornormally holding said elements in to the lower punch during the loadingoperation.

cavity-forming position, a reciprocative punch positioned to enter theother end of said cavity, means for cyclically driving saidreciprocative punch into said cavity and for withdrawing the sametherefrom to permit filling of said cavity, and speed-reducing drivingmeans controlled by the movement of said reciprocative punch towardssaid die for positively mo ving said die towards said stationary punch,at a speed bearing a definite relation to the speed of movement of saidreciprocative'punch.

3. A molding press comprising, in combination, a reciprocative diehaving a mold cavity formed therein, a normally stationary punchpositioned in one end of said cavity, means for normally holding saidreciprocative die-in cavity-forming position with respect to saidstationary punch, a reciprocative punch positioned to enter the otherend of said, cavity and to be withdrawn therefrom to permit filling ofsaid cavity, driving means for moving said reciprocative punch to entersaid cavity, driving means comprising a mechanical movement forpositively moving said reciprocaper punch, means for mounting andguiding said upper [punch for vertical reciprocating movement to enterthe upper end of said cavity and to be withdrawntherefrom to permitfilling of said cavity, driving means for reciprocating said upper punchthrough a molding cycle, driving means for moving said die towards saidlower tive die towards said stationary punch at a speed less than thespeed of said reciprocative punch,

a and means for timing the operation of said two driving means wherebysaid second driving means becomes efiective substantially at the instantwhen said reciprocative punch enters said cavity.

4. A molding press according to claim 1 wherein saiddie moving meanscomprises a pivoted lever having an arm thereof arranged in the path oftravel of a part moving with said reciprocative punch and beingoscillatable thereby, and

- 'a'connection from said lever to said reciprocating die against theaction of said biasing means.

6. A'molding press according to claim 1 wherein said die moving meansincludes a movable operating element positioned in the path of travel ofa part moving with said reciprocative punch and'b'eing engaged by saidpart at substantially thejinstant when said reciprocative punch ente'rs'said die. 1

7. A molding press comprising, in combination, a die table witha diemounted thereon having a mold cavity open at the top and bottom, meansfor guiding said die table for vertical reciprocatiom'a lower punchpositioned to close thelower end of said cavity and being mountedforjvertical reciprocation into said cavity to eject am'olded articletherefrom, means for normally biasingv said lower punch downwardlyagainst a stop}. means for normally biasing said die table upwardlyagainst a stop to normally maintain said' die table in a predeterminedposition with respect to said lower punch, an upper punch, means formounting and guiding said upper punch for vertical reciprocatingmovement to enter the upper 'end of said cavity and to be withdrawntherefrom to permit filling of said cavity,

- an oscillatable pivoted lever, a connection from said pivoted lever tosaid die table for reciprocating said table by oscillation of saidlever, and an element movable with said upper punch and positioned toengage and oscillate said lever on the downward movement or said punch.

8. A molding press comprising, in combine-.- tion,.a die havinga moldcavityopen at the top I and bottom, means for guiding said die forvertical reciprocation, a lower punch positioned to close the lower endof said cavity and being mounted for vertical reciprocation into saidcavity toeiect a molded article therefrom, means for normally biasingsaid die upwardly against a stop to normally maintain said die in apredetermined position with respect to said lower punch, an uppunchagainst said biasing means at a lower speed than the speed of movementof the upper punch on its downward movement, means for timing theoperation of the second driving means with respect to the first drivingmeans whereby the cycle of movement of said die begins substantially atthe instant when the upper punch enters the die and ends substantiallyat the instant when the upper punch leaves the die.

9. A molding press comprising, in combination, a die having a moldcavity formed therein,

a normally stationary punch positioned in said cavity and having alongitudinal bore formed therein, means for mounting said die forreciprocation with respect to said normally stationary punch, acore-rodpositioned within the bore of said punch and extending into saiddie, and means for supporting said core-rod in fixed re-, lation to saiddie, whereby said core-rod reciprocates with said die.

10. A molding press comprising, in combination, a die having a moldcavity formed therein,

a normally stationary punch positioned in said cavity and having alongitudinal bore formed therein, means for mounting said die forreciprocation with respect to said normally stationary punch, a core-rodpositioned within the bore of said punch and extending into said die,and means for supporting said core-rod from said die support in fixedrelation to said die while permitting reciprocation of said punch toeject a molded article from said cavity.

11. A molding press comprising, in combination, a die having a moldcavity formed therein, a reciprocative support for said die, a normallystationary punch positioned in one end of said cavity and having alongitudinal bore-formed therein, a core-rod positioned within the boreof said punch and extending into said die, means for supporting saidcore-rod from said die, support in fixed relation to said die whilepermitting reciprocation of said punch with respect to said die to ejecta molded article from said cavity, a

reciprocative punch positioned to enter the other end of said cavity andto be withdrawn therefrom to permitfilling of said cavity, driving meanswherein saidstationary punch has an'axial bore for moving saidreciprocative punch to enter said cavity, driving means for moving saidreciprocative die towards said stationary punch at a speed less than thespeed of said reciprocative punch, and means for timing the operationof" said two driving, means whereby said second driving means becomeseffective substantially at the instant when said reciprocativepimch'e'nters said cavity.

12. A molding press according to claim 1 formed therein, and including acore-=rod positioned in the bore of said punch and extending into saiddie, and means for supporting said corerod in fixed relation to saiddie.

. J, s'roxns, JR.

L. H. BAILEY;

